Influence of Landscape and Lake Characteristics on Long‐Term Water‐Level Responses in Shallow Lakes of the Sub‐Humid Boreal Plains, Canada

Abstract Shallow lakes are important ecosystems highly susceptible to water‐level fluctuations and desiccation caused by climate cycles and anthropogenic pressures. To better predict and manage the impacts of disturbance we examined the natural variability over a 20‐year period, that spans the range of long‐term (decadal) weather cycles, and the controls on water‐level deviation (WLD) of 26 shallow lakes that include all configurations of lake types and glacial landscapes typical in the Boreal Plains (BP) of Canada. Water budgets and hydrochemical analyses show that dominant lake water‐budget components vary spatially and temporally with different geological settings and land covers that influence the scale and magnitude of lake‐groundwater connectivity and surface‐water inflow. However, over decadal weather cycles similar ranges in WLD were observed across all glacial geologies and shallow lake types. Lake geometry and evaporation interacted with lake‐catchment characteristics to further impact the dynamics and memory of water levels to interannual and decadal weather patterns. In all lake‐catchment types, lake bathymetry and outflow sill elevation determined overall storage which controls maximum water level elevation during wet years and extent of desiccation during drought years. This research demonstrates that in sub‐humid glaciated continental landscapes, such as the BP, lake management strategies founded on lake permanence and fluctuation magnitudes are of limited value. Rather, focus should be placed on documenting the long‐term WLD and considering the interaction of landscape characteristics and internal lake mechanisms that enable different lake types in such heterogeneous landscapes to recover and persist over decadal meteorological cycles.